The invention relates to a system for interconnecting medium-voltage or high-voltage electrical cells housed in shielded, hermetically sealed and gas-insulated enclosures, which include sealed bushings whose respective axial conductors each have one accessible outside connecting end. The system is designed to interconnect conductors of two adjoining cells when the conductors of one cell are aligned with those of the other cell so that a conductor of one cell is aligned with a conductor of an adjacent cell and the outside connecting ends of the conductors of adjacent cells which are aligned in pairs are close together.
A system of the above kind is described in particular in European Patent EP-0 520 933 in which the bushings, which are carried by two adjoining enclosures and which have their axial conductors aligned, each include a frustoconical opening which is open towards the outside of the enclosure carrying it. An elastomer material connecting sleeve which has a double conical shape on the outside surrounds an interconnection device which electrically connects together the axial conductors of the bushings. The sleeve is compressed between the two bushings, with each of which it forms a frustoconical seal. The interconnection device is made up of conductive members whose ends are pressed outwards by peripheral springs around the outside connecting ends of two axial conductors to be interconnected. Thus the outside connecting ends of conductors aligned in pairs of adjoining enclosures are interconnected by means of modules of the interconnection system, each of which includes an interconnection device accommodated in an electrical insulation structure essentially consisting of a sleeve, as described above.
Moving an enclosure which is not at the end of a succession of aligned enclosures interconnected by means of the above system necessarily implies moving at least one of the adjoining enclosures and extracting the sleeves and the interconnection devices of all the modules between the enclosure to be moved and the adjoining two enclosures. What is more, unless all the enclosures on one side of an enclosure to be removed are moved, it cannot be removed without working inside at least one enclosure, which is filled with a protective gas which as a general rule must not be allowed to escape.
German Patent Application DE-19737429 describes a system which does not have the drawbacks of the system described above.
The connecting ends of the aligned axial conductors to be interconnected, which are carried by two bushings mounted on adjacent enclosures, project out from the enclosures as respective asymmetrical longitudinal flats. An interconnection device consists of a removable elongate conductive member whose ends have flats complementary to those on the conductors, so that the flats of the member can be screwed to those of the conductors. The removable member can be mounted and demounted from the outside, without moving any of the adjacent enclosures sideways, in particular in the event of replacing an enclosure. An electrical insulation structure must of course be associated with the conductive member of an interconnection device. It consists of an insulative sheath which covers the greater part of the member, but not its ends, and two sleeves mounted at opposite ends of the sheath and partly covering it. The sleeves are placed against the bushings from which the outside connecting ends of the conductors project, to establish continuity of insulation, which leads to some complexity and to the use of a large number of components.
The object of the invention is to provide a simple system for interconnecting medium-voltage or high-voltage electrical cells housed in shielded, hermetically sealed and gas-insulated enclosures, which system costs little to manufacture and use, entailing neither manipulation of gases nor lateral displacement of adjoining cells to replace a cell at a position intermediate between the ends of the row of cells.
The interconnecting system is constituted by modules, with each module being disposed between two medium-voltage or high-voltage electrical cells housed in shielded, gas-insulated and hermetically sealed enclosures which include sealed and insulative bushings, the respective axial conductors of said bushings being aligned in pairs and each having an accessible outside connecting end, two adjacent ends of axial conductors of adjoining bushings being electrically connected together by an interconnecting device constituting the system and surrounded by a tubular electrically insulating structure that is approximately coaxial with the axial conductors and constituted by a flexible insulative sleeve of elastically adaptable length, each annular end of a sleeve being fixed to a bushing by removable fixing means.
According to a feature of the invention, the sleeve has a longitudinal central portion which includes a projecting annular fold forming a return spring, and in that said sleeve has, between said central portion and at least one of its two annular flat ends, a longitudinal zone which includes a re-entrant annular fold so that the inside surface of said sleeve is locally in contact with an axial conductor at said zone, said inside surface being covered by a semi-conductive layer that is put to the same potential as the axial conductors.
According to another feature of the invention each interconnecting system includes an interconnection device mounted so that it can be moved in translation on the outside connecting end of a first axial conductor which projects outwards by an amount slightly less than the distance between the adjoining bushings of said conductors, so that it can be partially housed inside a cavity provided at the outside connecting end of each of the two aligned axial conductors electrically connected by the device, the outside connecting end of the first axial conductor including a cavity whose depth is chosen to enable the interconnection device to be withdrawn into it by movement in translation to disconnect the two aligned axial conductors.
In a first embodiment of the invention the interconnection device of a system includes a bush which has a cylindrical body extended by a threaded bore which screws into a threaded bore at the closed end of a stepped blind end cavity provided for the bush in the outside connecting end of the first axial conductor to be connected, the cylindrical body of the bush continuing to be electrically connected by means of sliding contacts to the inside of the corresponding diameter stage of the cavity, from which it protrudes more or less according to how far in the bush is screwed, and the projecting end of the cylindrical body of the bush coming into sliding contact with a blind cavity of corresponding diameter formed at the outside connecting end of the second axial conductor, into which said cylindrical body end penetrates when unscrewed sufficiently and connects the two axial conductors with which the cylindrical body of the bush is then simultaneously in contact.
In a first variant of the invention the interconnection device of a system includes an assembly of two contact half-shells in contact which are elastically spread apart in order to come separately into contact with the outside connecting ends of two axial conductors to be connected, in the blind end cavity of each of said conductors, from a closely spaced position of the half-shells which enables them to penetrate into said end cavities and which is obtained by the action of a screw on which the two half-shells are mounted. The assembly can be moved longitudinally at the greatly projecting outside connecting end of the first axial conductor between a position enabling the two half-shells to be kept in contact with the axial conductors in the cavities of which they are partially inserted and a position in which the two half-shells are inserted only in the cavity at the outside connecting end of the first axial conductor.
In a second variant of the invention the interconnection device includes an assembly of two contact half-shells in contact which are elastically spread apart in order to come separately into contact with the outside connecting ends of two axial conductors to be connected, of the hollow tube type, at an outside connecting end of the tube formed by each conductor, from a closely spaced position of the half-shells which enables them to penetrate into the adjoining ends of the two tubes and which is obtained by the action of a screw on which the two half-shells are mounted. The half-shells are mounted on the shank of the screw by means of which they are fastened to an outside connecting end of the tube of the first axial conductor which projects outwardly by an amount corresponding to the distance between the adjoining two bushings through each of which one of the tubes passes. The assembly can be moved longitudinally at the outside connecting end of the first axial conductor between a position enabling the two half-shells to be kept in contact with the two tubes into which they are partially inserted and a position in which the two half-shells are inserted only in the cavity at the greatly projecting outside connecting end of the tube forming the first axial conductor.